Our understanding of retinal physiology has increased markedly over the past ten years with the growing sophistication of electrophysiological techniques. Most of the research effort has been devoted to the study of the functional properties of photoreceptors, horizontal cells and ganglion cells. However bipolar cells and amacrine cells have received considerably less attention, especially in the retinas of color discriminating animals. As a result, very little is known about the way bipolar and amacrine cells differentiate, encode and transmit chromatic and luminosity information. In this project intracellular recordings will be obtained from single bipolar cells and amacrine cells of the turtle retina. I propose to identify and characterize the neural interactions responsible for the color-opponent center of chromaticity bipolar cells. In addition, the adaptive properties of luminosity bipolar cells will be studied in order to identify the source of neural adaptation occurring proximal to the photoreceptors. Amacrine cells will be studied to differentiate color- and non color-coded cells, their respective response characteristics, receptive fields, adaptive effects of peripheral stimulation and spectral input. Finally, the synaptic organization of L- and C-type amacrine cells will be studied by electron microscopic examination of amacrine cells iontophoretically stained with Procion Brown. The goal of this project is to provide much needed data on the spatial, chromatic and adaptive properties of bipolar and amacrine cells.